rs6000.h: (rs6000_sched_insert_nops): support new flag -minsert-sched-nops.

        * config/rs6000/rs6000.h: (rs6000_sched_insert_nops):
        support new flag -minsert-sched-nops.
        (DEFAULT_SCHED_FINISH_NOP_INSERTION_SCHEME): Define.
        * config/rs6000/rs6000.c: (rs6000_sched_insert_nops):
        support new flag -minsert-sched-nops.
        (is_cracked_insn, is_microcoded_insn): New functions.
        (rs6000_sched_finish): New function.
        (rs6000_issue_rate): Return 5 for power4.
        (get_next_active_insn, insn_terminates_group_p): New
        functions.
        (is_costly_group, force_new_group): New functions.
        (redefine_groups, pad_groups): New functions.
        (rs6000_variable_issue): Use new functions.
        * doc/invoke.texi (-minsert-sched-nops): Document new
        option.

From-SVN: r72707